1. This is this cat
2. This is is cat
3. This is how cat
4. This is to cat
5. This is keep cat
6. This is a cat
7. This is fool cat
8. This is busy cat
9. This is for cat
10. This is forty cat
11. This is seconds cat
Now go back and read the third word in each line from the top down, and I bet you can't resist sharing it.